Donetsk, Ukraine: Ukrainian troops and pro-Russian forces were engaged in fresh clashes in the eastern city of Donetsk on Friday as they traded blame over the death of a foreign aid worker four weeks into their shaky truce.

Parliament speaker Oleksandr Turchinov claimed the ceasefire has been breached “over a thousand times” while the Kiev government blamed the separatists for the death of a Swiss Red Cross employee on Thursday evening.

The shelling of the International Committee of the Red Cross office in Donetsk, which prompted a firm rebuke from UN Secretary General Ban Ki-moon, was described as an “act of terror” by Kiev.

“This terrorist act cannot be justified,” Ukraine’s foreign ministry said in a statement. “Bandits and terrorists, in a barbaric way, dared to take up arms against those who came ... with a humanitarian mission.”

Kiev’s military said in a statement the rebels have repeatedly fired on central Donetsk “to discredit the anti-terrorist operation”.

Ten civilians were killed on Wednesday when a school and bus stop was shelled on the first day of class.

The rebels blamed the recent attack on indiscriminate shelling by the Ukrainian army from distant positions.

“The Ukrainian army is firing at Donetsk for the second day in a row from Uragan (Hurricane multiple rocket launcher) systems,” Andrei Purgin, deputy prime minister of the self-proclaimed Donetsk People’s Republic, told AFP.

“Firing from such systems is not targeted, they simply hit a general area, along with everyone in it.”

“They could have fired from many areas, but we believe it was from Krasnogorovka,” a town 20 kilometres west of Donetsk.

ICRC said in a statement the victim was 38-year-old Laurent DuPasquier, who had worked on aid missions in countries ranging from Pakistan to Papua New Guinea and came to Ukraine six weeks ago to be part of the group’s 20-strong staff in Donetsk.

The fighting in Donetsk, once a huge industrial city of one million, resumed after a relatively quiet night on Friday in several neighbourhoods, according to the city hall, who said five civilians had been injured over the past 24 hours.

A city hall spokesman said the fighting was so far confined to the airport in the northern outskirts, where the rebels have spent days trying to push out a Ukrainian contingent.

Its long runway would give the rebels the ability to land large planes, but Kiev said last month that the damaged facility would be unable to service or fuel aircraft.

Kiev said it was still in control of the airport on Friday after receiving an injection of fresh troops and armour.

AFP journalists heard two loud explosions from the city centre on Friday morning.

Locals said they have observed no change since the truce was signed.

“We’ve been under fire since May 26,” said 78-year-old Raisa Golovichkina. “Both sides are guilty of all that’s happened to us.”

With the toll from five months of conflict in the east now over 3,200 people, the UN secretary general said he was “saddened and disturbed” about the latest aid worker death.

“The Secretary-General is seriously concerned over the dangerous surge of fighting,” Ban’s spokesman said. “These recent tragic incidents underscore the fragility of the current ceasefire,” he added.

“Political and diplomatic efforts must be urgently redoubled toward this end,” he said.

The European Union earlier expressed concern for the unravelling violence, which has killed nearly 70 people since the 12-point truce was signed on September 5.

The agreement, which was further elaborated on September 19, commits Kiev and the rebels to create a buffer zone 30 kilometres (20 miles) wide.

“Observation of the ceasefire is a necessary step for the much-needed restoration of law and order in the east of Ukraine,” a spokesman for the EU’s diplomatic service said in a statement on Thursday.